Electrical cable



9, 1938. G. A. SEELEY 2,126,290

ELECTRICAL CABLE Filed Sept. ll, 1936 FIG.

INVEN T0,?

6.4. SEELEY BY A TTORNEY Patented 9, 1938 PATENT OFFICE ELECTRICAL CABLE George A. Seelcy, Baltimore, Md., minor to -Western Electric Company, Incorporated, New

York, N. Y., a corporation of New York Application September 11, 193 Serial No. 100,211

3 Claims.

This invention relates to electrical cables and more particularly to a coaxial cable in which one conductor is substantially a hollow metallic cylinder enclosing another metallic conductor of smaller diameter spaced from and supported in the cylinder by spacing members of insulating material.

It may be desirable in some instances, to lay up two or more such coaxial conductor pairs in a compound cable, either alone or with other con= ductor units of other types. in such a case, the coaxial units will be stranded or intertwisted together, which may present some diitlculties be cause of the inherent torsional rigidity of the cylindrical outer conductor of a coaxial pair.

Coaxial conductor pairs also are frequently used to form an outgoing and return circuit for an alternating electrical current oi high frequency. it is therefore particularly essential that the inner surface of the outer conductor, which. faces and is nearest to the inner conductor, shall be smooth, continuous and free from irregularities so far as may he. I

Objects of the present invention are to "provide a coaxial conductor pair which shall he simple in structure, easy to manufacture, relatively low torsional rigidity at least in one direction of pnssible twist, and having an outer conductor in hei'ently smooth Within.

One embodiment of the invention contemplates a coaxial conductor having any suitahle form inner or axial conductor such as solid wire, hollow strand, or compound strand, .with a plu rality of spacing members or insulating material thereon, and with an outer conductor of cylindrical form on the spacing members, the outer conductor being a strip or tape oi metal formed longi tudinally into a cylinder and having its edges meeting and held in place by integral means on terior to the cylinder, but preferably such as to permit of longitudinal displacement or? the abutted edges of the tape relatively to each other, while preventing any radial displacement of the edges.

Other objects and features oi the invention will appear from the following detailed description of one embodiment thereof taken in connection with the accompanying drawing in which the same reference numerals are applied to identical parts in the several figures and in which Fig. l is a broken view in side elevation of a part of a coaxial conductor pair constructed in accordance with the invention;

Fig. 2 is an end view thereoi;

Fig. 3 is a side view on a reduced scale of a portion of the pair after being twisted;

Fig. 4 is an end view thereof;

Fig. 5 is a plan view of a portion oi a tape to be formed into an outer conductor, and

Fig. 6 is an end view thereot.

In the embodiment of the invention herein disclosed, a coaxial conductor pair comprises an in ner or axial conductor to, a plurality of slotted spacing disks it, it mounted on the inner condoctor at intervals therealong, and a cylindrical outer conductor 62 resting on the peripheries of the disits M, ii to be supported on and spaced from the inner conductor thereby. The inner conductor herein disclosed is preferably a smooth solid circularly cylindrical wire of copper, but may be of other metal or of other form if desired, e. g., a cylinder, a plurality of associated strands, or any other practicable form, The dislgs ii, it may be thought of as molded or formed or cut from any suitable insulating material, e. g., artificial resin, rubber, cellulose plastic, or the lilac and may have any form suitable for the purpose.

The outer conductor (32 is a strip or tape of able material such as copper, bronze, aluminum or other appropriate conductive substance, stormed over the peripheries of the disks it, it into cylinder supported thereon, the cylinder being in this instance of circular cross-section, if desired it may in some cases be lfiOll-Clifillllf The strip is formed along both edges thereof spaced, integral, outwardly projecting teeth it; These teeth M, i i are oilset icy about the thickness of the tape toward that side of the tape which forms the outer surface of the cylindrical outer conductor. The true edges is, it of the heing aout'ted to form a seam l'l, the teeth i l oi each edge overlie the other edge, so that the teeth of each edge hold the other edge down.

if in the manufacture of the tape shown in 5 and 6, the teeth are cold worked (as by being swedged while being cut with a punch and die, cutting rolls, or the like), they may, in the process of being formed into the cylindrical conductor, be more or less deeply imbedded into the material of the opposite edges, thus still more securely interloching the edges along the seam ll, which however, increases the torsional rigidity of the formed conductor.

However in the embodiment herein disclosed, it is desired to have the outer conductor torsion ally flexible with respect to a specific amount of left hand twist, and laterally flexible after being twisted. Hence the teeth is, M are so procurtioned and so disposed relatively to each other that when the conductor is first formed as shown in Figs. 1 and 2, with the seam ll distrust-{ii along a straight geometrical element oi the cylindrical. iorm of the conductor, each tooth one edge substantially abutted laterally of against one corresponding tooth or the other edge, the oil? edge l5 being Just to the left those of c ill seen in Fig. 1. These abil'tted palm corresponding teeth are further spaced apart along the seam I].

When the conductor pair is now twisted, as for example in being laid up with one or more iiinr pairs in a compound cable, the edges iii to slide along each other and the teeth who lions such as shown in Figs. 3 d d, as the ill I! is changed from a straight he to a heliii. s the teeth may be distributed at substantially intervals along the helical seam oi? the .ed unit.

some instances, the teeth may preferably be t rmed to stand at spaced intervals along i ight seam. The unit may then be twisted ei "her way;

Furthermore ii the pair is not to be twisted, but it is desired to have the seam helical, the tape may be wrapped spirally instead of being formed longitudinally over the disks 'l I, H, in which case the teeth of the tape will be original] located to fall as shown in Fig. 3.

A cable as shown in Fig. 3, or comprising units such as shown in Fig. 3, will have much greater flexibility both in torsion and in nexure than an analogous structure with the edges of the tape welded, soldered or immovably interlocked, yet neither edge can lift above the other radially to produce any internal ridge or protuberance to harm the desired electrical properties of the pair.

It will be clear that the embodiment of the invention herein disclosed is only illustrative and may be modified and departed from in many ways without departing from :the spirit and scope of the invention as pointed out in and limited solely by the appended claims.

What is claimed is: w

1. In a coaxial conductor pair the combination with an axial conductor otvan outer hollow con- .in iii, Ii 53, ii iii) doctor theronrcnod and comprismg a metal tape outer of other edge, the widths of the spaces between consecutive projections on either edge greater than the widths oil the pro jectiono on the other edge and the projections on either edge overlapping the other edge between consecutive projections oi the other edge, the parts being so proportioned and arranged that when the conductor pair is twisted each edge and its projections free to slide along the other edge to provide torsional flexibility, while the seam cannot open. radially.

2. In a coaxial conductor pair the combination with an axial conductor and spacing members thereon oi an outer hollow conductor therecround and comprising a metal tape iformed into a tube with the edges the tape abutteci together to form a seam, each edge of. the tape having projecticns thereon overlying the outer side oi" the other abutting edge, the widths of the spaces between consecutive projections on either edge being greater than the widths of the projections on the other edge and the projections on either edge overlapping the other edge between consecutive projections of the other edge, the parts being so proportioned and arranged that when the conductor pair is twisted each edge and its projections are free to slide along the other edge to provide torsional flexibility, while the seam cannot open radially.

3. In a coaxial conductor pair the combination with an axial conductor and spacing members thereon of an outer hollow conductor therearound and comprising a metal tape formed into a tube with the edges of the tape abutted together to form a seam, each edge or the tape having projections thereon overlying and slidable on the outer side of the other edge, so that when the conductor pair is twisted each edge and its projections are free to slide along the edge to provide torsional flexibility, while the seam cannot open radially.

GEORGE A. SEELEY. 

